1. Field of the Invention
The present invention relates to a signal processing apparatus and a signal processing method which perform signal processing for expanding a service area having a sound-image localization effect on audio signals during sound reproduction for giving a virtual sound-image localization effect and to a storage medium that stores a program for realizing such signal processing.
2. Description of the Related Art
As disclosed in Laid-open Japanese Patent Application Publication No. 5-260597, for example, virtual sound-image localization processing is typically performed to virtually localize a sound image at a position that is different from the positions of speakers that actually reproduce sound, for example, to localize sound images at a rear left position and a rear right position, by reproducing sound by using two (left and right) channel front speakers.
In order to virtually localize a sound source, an ideal listening position of a listener relative to multiple speakers (e.g., for two (left and right) channels) to be disposed is pre-determined and transmission functions (G) of sounds output from the speakers (which actually reproduce the sounds) to both (left and right) ears of the listener and transmission functions (H) of sound output from a virtual sound image position to the both ears are pre-measured as transmission functions of sounds output from the speakers to the both ears of the listener who is at the ideal position. During actual processing, transmission functions based on the transmission function (G) and (H) are integrated, and the resulting signals are supplied to the speakers for output.
With this arrangement, only the use of, for example, two (left and right) channel front speakers allows a sound image to be virtually localized at arbitrary positions at, for example, a rear left position and a rear right position of the listener.